Ice cream machine having an auxiliary evaporation tank

ABSTRACT

An ice cream machine for cooling liquid ice cream into frozen ice cream includes an evaporator having a cylindrical cooling tank and an auxiliary tank. The auxiliary tank ensures that the cylindrical cooling tank is flooded with liquid refrigerant during normal operation. The flooding of the cylindrical cooling tank provides more efficient and even cooling in an interior cooling chamber. The more efficient cooling allows the ice cream machine to utilize a smaller compressor, thereby reducing the cost and energy consumption of the ice cream machine. The auxiliary tank can be a coil of tubing or a cylindrical container positioned above the cylindrical cooling tank.

This is a continuation application of application Ser. No. 08/602,302 ofRoss, Harold F. filed Feb. 16, 1995 which is hereby abandoned.

FIELD OF THE INVENTION

The present invention relates to refrigeration or cooling systems. Moreparticularly, the present invention relates to an ice cream machinehaving an auxiliary evaporator tank.

BACKGROUND OF THE INVENTION

Ice cream machines as well as other systems for cooling or freezing foodstuffs, condiments, or other materials, typically include an evaporatorsituated proximate the material being chilled. For example, in ice creammachines, liquid ice cream is typically inserted in a freezing chamberadjacent the evaporator and is removed from the freezing chamber assolid or semi-solid ice cream. The evaporator removes heat from thefreezing chamber as a liquid refrigerant such as FREON®, ammonia, HP62,502 or other liquid having a low boiling point changes to vapor inresponse to the heat from the liquid ice cream. Typically, theevaporator is partially filled with vapor as the liquid refrigerantboils (e.g., becomes vapor) in the evaporator..

Since most heat transfer occurs when the liquid refrigerant is changedto vapor, the partially filled evaporator is less efficient than aflooded evaporator (e.g., an evaporator filled entirely with liquidrefrigerant). The partially filled evaporator also tends to unevenlycool the ice cream because the parts of the evaporator which are filledwith vapor are not able to cool as effectively as the parts of theevaporator filled with liquid. Further, prior art ice cream machines aredisadvantageous because the pressure does not remain constant in theevaporator due to the accumulation of vapor. The inefficienciesresulting from the partially filled evaporator require the ice creammachine to use a larger, more expensive, and less energy efficientcondenser or pump.

Thus, there is a need for an ice cream machine which utilizes a floodedevaporator. There is also a need for an evaporator which provides evencooling in the freezing chamber.

SUMMARY OF THE INVENTION

The present invention relates to an ice cream machine including acylindrical evaporator having a refrigerant input and a refrigerantoutput, an evaporator reservoir having a reservoir input and a reservoiroutput, a compressor having a compressor input and a compressor output,and a condenser having a condenser input coupled to the compressoroutput and a condenser output coupled to the refrigerant input. Thecylindrical evaporator has an interior surface defining a coolingchamber which has an ice cream input and an ice cream output. Thereservoir input is coupled to the refrigerant output. The evaporatorreservoir is located above the cylindrical evaporator with respect togravity. The compressor input is coupled to the reservoir output. Therefrigerant travels from the condenser through the cylindricalevaporator and the evaporator reservoir to the compressor. Therefrigerant boils from its liquid state to a vapor state. Therefrigerant accumulates as a vapor in the evaporator reservoir, therebyproviding superior cooling in the cylindrical evaporator.

The present invention also relates to a cooling system for cooling afood stuff including a compressor, and evaporator in the shape of ahollow cylinder, and an auxiliary evaporator means. The evaporator has arefrigerant input and a refrigerant output and contains the food stuff.The auxiliary evaporator means is positioned above the evaporator withrespect to gravity and receives liquid refrigerant from the refrigerantoutput of the evaporator. The auxiliary evaporator means provides thevapor refrigerant to the compressor. The compressor receives the vaporrefrigerant and provides the liquid refrigerant to the evaporator.Superior cooling of the food stuff in the evaporator is obtained bycompletely filling the evaporator with the liquid refrigerant. Theauxiliary evaporator means cause the evaporator to be completely filledwith the liquid refrigerant.

The present invention also relates to an improved ice cream freezingmachine including a tubular evaporator, a compressor, and a condenser.The tubular evaporator has a refrigerant input at a bottom side of theevaporator, a refrigerant output at the top side of the evaporator, andan interior surface defining an interior cooling chamber. The interiorcooling chamber has an ice cream input and an ice cream output. Thecompressor has a compressor input and a compressor output. The condenserhas a condenser input coupled to the compressor output and a condenseroutput coupled to the refrigerant input. The improvement includes anevaporator reservoir having a reservoir input coupled to the refrigerantoutput and a reservoir output coupled to the compressor input. Theevaporator reservoir is located above the cylindrical evaporator withrespect to gravity. A refrigerant travels from the condenser through thecylindrical evaporator and the evaporator reservoir to the compressor.The refrigerant is a liquid in the cylindrical evaporator. Therefrigerant accumulates as a vapor in the evaporator reservoir, therebyproviding superior cooling in the cooling chamber.

In one aspect of the present invention, an auxiliary tank is positionedabove (e.g., located higher than) the evaporator. The auxiliary tank maybe a coil of copper tubing or a container such as a cylindrical orspherical reservoir. The auxiliary tank ensures that the cylindricalevaporator is flooded with liquid refrigerant such as FREON or HP62.According to another aspect of the present invention, the evaporator isa cylindrical evaporator having an interior cooling chamber. Liquid icecream is inserted into the interior cooling chamber and exits thecooling chamber as solid ice cream. Alternatively, yogurt, condiments,or other food stuffs may be chilled or frozen in the cooling chamber.

Preferably, low pressure liquid refrigerant enters the cylindricalevaporator at a bottom side and exits the cylindrical evaporator at atop side. The low pressure liquid refrigerant boils and accumulates asvapor in the auxiliary tank. The refrigerant returns to the compressoras low pressure vapor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereafter be descried with reference to theaccompanying drawings, wherein like reference numerals denote likeelements, and:

FIG. 1 is a schematic diagram illustrating an ice cream machine inaccordance with an exemplary embodiment of the present invention;

FIG. 2 is a more detailed side view schematic diagram of the cylindricalcooling tank and auxiliary tank illustrated in FIG. 1; and

FIG. 3 is a cross-sectional view of the cylindrical cooling tankillustrated in FIG. 2 at line 3--3.

DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENT OF THEPRESENT INVENTION

A cooling system or ice cream machine 10 is diagramically shown inFIG. 1. Ice cream machine 10 includes an evaporator 20, an expansionvalve 22, a solenoid valve 24, a sight glass 26, a filter 28, acondenser 30, a compressor 32, an accumulator 34, and a valve 36.Evaporator 20 includes a cylindrical cooling tank 38 and an auxiliarytank 48.

Cylindrical cooling tank 38 includes a refrigerant input 40, arefrigerant output 42, a liquid ice cream input 44, and a solid icecream output 46. Auxiliary tank 48 includes a liquid refrigerant input52 and a vapor refrigerant output 54. Cylindrical cooling tank 38includes a cooling chamber 56 defined by an interior surface, wall ortube 57 of tank 38.

Auxiliary tank 48 is positioned above with respect to gravity or overcylindrical cooling tank 38. Additionally, liquid refrigerant input 52is located above refrigerant output 42, and refrigerant input 40 of tank38 is located beneath refrigerant output 42 of tank 38. Vaporrefrigerant output 54 of tank 48 is located above liquid refrigerantinput 52 of tank 48.

With reference to FIGS. 2 and 3, cylindrical cooling tank 58 ismanufactured from an outside tube 59 having an inside diameter of 4.75inches, an outside diameter of 5 inches, and a length of 27.75 inches,and an inner tube 57 having an inside diameter of 3.75 inches, anoutside diameter of 3.875 inches, and a length of 30 inches. Preferably,wall 58 is .125 inches thick. The volume of interior cooling chamber 56is approximately 331 cubic inches. The volume of an evaporator chamber61 between outer tube 59 and inner tube 57 has a volume of approximately165.1 cubic inches. Auxiliary tank 48 is preferably a piece of tubing orother container having a length of 7 inches, a width of 2 inches, and adepth of 4 inches. The approximate volume of tank 48 is 56 cubic inches.

The operation of ice cream machine 10 is described below with referenceto FIGS. 1-3. Compressor 32 provides high pressure vapor refrigerant tocondenser 30. Ice cream machine 10 may utilize a refrigerant such asammonia, FREON, HP62, or other substance having a low boiling point. Thetype of refrigerant is not a limiting factor with respect to the presentinvention.

Condenser 30 provides high pressure liquid refrigerant through filter28, sight glass 26 and solenoid valve 24 to expansion valve 22.Expansion valve 22 provides low pressure liquid refrigerant toevaporator 20. More particularly, low pressure liquid refrigerant isprovided to refrigerant input 40 of cylindrical cooling tank 38. The lowpressure liquid refrigerant in cooling tank 38 is boiled due to the heatfrom cooling chamber 56, to form low pressure vapor refrigerant whichaccumulates in auxiliary tank 48. The low pressure liquid refrigerant incylindrical cooling tank 38 preferably cools or freezes the liquid icecream from input 44 in cooling chamber 56. Although, ice cream isdisclosed, other food stuffs, substances, or condiments may be utilizedin machine 10.

More particularly, the warmer liquid ice cream with respect to theliquid refrigerant provided to liquid ice cream input 44 is cooled andprovided as frozen ice cream at ice cream output 46 as the low pressureliquid refrigerant is transferred from liquid to vapor. The low pressurevapor refrigerant collects via auxiliary tank 48. Preferably, system 10is provided with enough liquid refrigerant so that all of cylindricalcooling tank 38 is filled and auxiliary tank 48 is two-thirds toone-half filled with liquid refrigerant during normal operation of icecream machine 10.

The low pressure vapor refrigerant in tank 48 travels from vaporrefrigerant output 54 through valve 36 and accumulator 34 to compressor32. Compressor 32 changes the low pressure vapor refrigerant to highpressure vapor refrigerant and provides the high pressure vaporrefrigerant to condenser 30. Condenser 30 changes the high pressurevapor refrigerant to high pressure liquid refrigerant which is providedto valve 22.

The flooding of tank 38 advantageously provides even cooling as liquidice cream travels from ice cream input 44 to ice cream output 46 becausethe temperature and pressure of the low pressure liquid refrigerant incylindrical cooling tank 38 is maintained constant. Therefore, the icecream in cooling chamber 56 is chilled evenly wherever it is verticallylocated within cooling chamber 56. Prior art cooling tanks tended tochill the ice cream unevenly near the top of the evaporator becauseliquid refrigerant was only located on the bottom of the evaporator.

The use of such an advantageous evaporator 20 allows system 10 to bedesigned with a relatively small compressor 32. The small size ofcompressor 32 makes ice cream machine 10 less expensive and more energyefficient. Preferably, auxiliary tank 48 may be a coil of copper tubinglocated above cylindrical cooling tank 38. Preferably, auxiliary tank 48is a tank located above cylindrical cooling tank 38 such as acylindrical or spherical tank, reservoir, can, or other container.Cylindrical cooling tank 38 preferably has almost three times the volumeof auxiliary tank 48.

It is understood that, while the detailed drawings and specific examplesgiven to describe the preferred exemplary embodiment of the presentinvention, they are for the purpose of illustration only. The apparatusof the invention is not limited to the precise details and conditionsdisclosed. For example, although food stuffs and ice cream arementioned, the invention may be utilized in a variety of refrigerationor cooling systems. Further, single lines for carrying liquidrefrigerant can represent multiple tubes. Additionally, although aparticular valve, accumulator, compressor, condenser and filterconfiguration is shown, the advantageous evaporator 20 may be utilizedin other cooling systems. Various changes can be made to the detailsdisclosed without departing from the spirit of the invention which isdefined by the following claims.

We claim:
 1. A frozen custard making machine, comprising:a cylindricalevaporator having a refrigerant input, and a refrigerant output, thecylindrical evaporator having an interior surface defining a coolingchamber, the cooling chamber having a custard input and a custardoutput, the evaporator having an outside surface, the outside surfaceand the interior surface defining an evaporator chamber, the refrigerantinput being below the refrigerant output, the refrigerant input and therefrigerant output being in fluid communication with the evaporatorchamber; an evaporator reservoir having a reservoir input and areservoir output, the reservoir input being coupled to the refrigerantoutput, the evaporator reservoir being located above the cylindricalevaporator with respect to gravity; a compressor having a compressorinput coupled to the reservoir output and a compressor output; and acondenser having a condenser input coupled to the compressor output anda condenser output coupled to the refrigerant input, whereby arefrigerant travels from the condenser through the cylindricalevaporator and the evaporator reservoir to the compressor, therefrigerant being a liquid in the cylindrical evaporator, therefrigerant being a liquid in the cylindrical evaporator reservoir,thereby providing superior cooling in the cylindrical evaporator.
 2. Thefrozen custard making machine of claim 1, wherein the evaporatorreservoir is a length of copper tubing significantly longer than adistance from the compressor to the evaporator reservoir.
 3. The frozencustard making machine of claim 1, wherein the evaporator reservoir is atank.
 4. The frozen custard making machine of claim 3 wherein the tankhas a volume at least .33 times a volume of the evaporator chamber ofthe cylindrical evaporator.
 5. The frozen custard making machine ofclaim 1, wherein liquid custard product is provided to the custard inputand frozen custard product is provided by the custard output.
 6. Thefrozen custard making machine of claim 1, wherein the evaporatorreservoir is two-thirds filled with the liquid.
 7. A frozen custardmaking system comprising:a compressor; an evaporator in the shape of ahollow cylinder, the evaporator having a refrigerant input and arefrigerant output, the evaporator having an interior surface defining acooling chamber for chilling a custard product, the evaporator having anoutside surface, the inside surface and the outside surface defining anevaporator chamber; and an auxiliary evaporator means, positioned abovethe evaporator with respect to gravity, for receiving a liquidrefrigerant from the refrigerant output of the evaporator and providinga vapor refrigerant to the compressor, the compressor receiving thevapor refrigerant and providing the liquid refrigerant to theevaporator, whereby superior cooling of the custard product in theevaporator is attained by completely filling the evaporator with theliquid refrigerant, the auxiliary evaporator means causing theevaporator to be completely filled with the liquid refrigerant.
 8. Thefrozen custard making system of claim 7, wherein the auxiliaryevaporator means is a length of copper tubing significantly longer thana distance from the compressor to the evaporator.
 9. The frozen custardmaking system of claim 8, wherein the copper tubing is wound in a coilabove the evaporator.
 10. The frozen custard making system of claim 7,wherein the auxiliary evaporator means is a cylindrical tank.
 11. Thefrozen custard making system of claim 10 wherein the tank has a volumeat least .33 times a volume of the evaporator.
 12. The frozen custardmaking system of claim 7, wherein the custard product is frozen in theevaporator.
 13. the frozen custard making system of claim 7, wherein theauxiliary evaporator means is two-thirds filled with the liquidrefrigerant.
 14. The frozen custard making system of claim 12, whereinthe auxiliary evaporator means is a length of copper tubing longer thanthe distance between the evaporator and the compressor.
 15. The frozencustard making system of claim 13, whereby the auxiliary evaporatormeans provides superior cooling in the evaporator.
 16. A custardfreezing machine comprising:a tubular evaporator having a refrigerantinput at a bottom side of the evaporator, and a refrigerant output at atop side of the evaporator, the tubular evaporator having an interiorsurface defining an interior cooling chamber, and an exterior surface,the interior surface and the exterior surface defining an evaporatorchamber having a volume, the cooling chamber having a custard input anda custard output; a compressor having a compressor input and acompressor output; a condenser having a condenser input coupled to thecompressor output and a condenser output coupled to the refrigerantinput; and an evaporator reservoir having a reservoir input coupled tothe refrigerant output, and a reservoir output coupled to the compressorinput, the evaporator reservoir being located above the cylindricalevaporator with respect to gravity, whereby a refrigerant travels fromthe condenser through the cylindrical evaporator and the evaporatorreservoir to the compressor, the refrigerant being a liquid in thecylindrical evaporator, the refrigerant accumulating as a vapor in theevaporator reservoir, thereby providing superior cooling in the coolingchamber.
 17. The custard freezing machine of claim 16, wherein theevaporator reservoir is a length of tubing substantially longer than thedistance between the evaporator and the compressor.
 18. The custardfreezing machine of claim 17, wherein the tubular evaporator is floodedwith the liquid and the evaporator reservoir is two-thirds filled withthe liquid.
 19. The custard freezing machine of claim 17, wherein thetubing is coiled.
 20. The custard freezing machine of claim 16, whereinthe auxiliary reservoir is a cylindrical tank.